I think if Canon prices and specs the camera well enough this could be very interesting.
Just imagine if Canon releases a system with a zoom or two and two or three prime lenses... Two bodies, one for a pro-sumer and the other aimed at high end professional. The low end one, priced at $5000-7500 with a solid AF system, LCD, maybe 50MP, etc...
The high end could be priced at $12,500 or so and include all the bells and whistles... 150MP, wireless transmitter built in for flashes, wifi for studio use, HDMI, etc... Ultimate studio camera.
The lenses, maybe offer something equivalent to the EF 24-70 and 70-200 as far as zooms go. Then offer equiv. 35, 85 and 135 prime options. Lenses at $2500-4500 each price wise...
This would make a system 'in reach' for somebody who can offset the costs of switching by selling off their EF lenses and EF bodies.
If priced way too high, I don't see it being that worthwhile for Canon. I know the sensors will be pricey, but it still should be somewhat affordable. I would seriously consider switching to a two lens, MF setup IF the price was right (and feature set on the limited prosumer body).
I am just dreaming here, but imagine that IQ from a MF, high MP sensor... Would be stunning... Especially if they can give in some serious ISO range (100-51,200 native, ISO 50 and 102,400 and 204,800 pushed).
If they can do that with a nice updated sensor that rivals what the D800 can do, people will eat it up.
Just thinking out loud here though.